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Objectives: To compare the ionised calcium measured on a portable analyser (iSTAT, Abbott) to a reference method., Materials and Methods: Blood samples from 39 apparently healthy dogs were analysed in duplicate using a portable analyser and a reference method (Radiometer ABL800 FLEX). Bland-Altman plots and Passing-Bablok regression were used to assess constant and proportional bias between the two instruments. A within-assay percentage coefficient of variation and total error (TE) was calculated for both analysers. The reference interval was calculated for the portable analyser using the robust method with confidence interval bootstrapping., Results: The Bland-Altman plot showed a -0.036 mmol/L difference between the two instruments (95% confidence limit -0.08 to 0.01 mmol/L; limits of agreement -0.07 to 0.006 mmol/L). Neither the Bland-Altman plot nor the Passing-Bablock regression (slope -0.03; 95% confidence interval -0.08 to 0.19 and intercept 1; 95% confidence interval 0.83 to 1.2) showed significant proportional bias. The coefficient of variation for the portable analyser was 1.08%, compared to 0.78% for the reference method with a total error of 3.5% for the portable analyser. The estimated population-based reference interval for ionised calcium using the portable analyser is 1.23 to 1.42 mmol/L., Clinical Significance: For the healthy dogs in this study, compared to the reference method, the portable analyser showed no significant bias for measurement of ionised calcium. Further studies including hyper and hypocalcaemic dogs are required to determine clinical impact of the use of this analyser., (© 2023 British Small Animal Veterinary Association.)

Two experiments were conducted using four strains of Leghorn pullets, namely Babcock, DeKalb, H & N, and Shaver. Pullets were grown on conventional or low protein diets fortified with additional amino acids. At 18 wk of age, 64 pullets from each strain and diet treatment were transferred to individual laying cages, using eight replicate groups of four adjacently caged birds. In a second experiment, pullets from the four strains were selected based on body weight at 18 wk of age (approximately 1,270 vs 1,650 g). Each weight group and strain was again represented by eight replicate groups of four birds. In Experiment 1, there were no strain or rearing diet effects on egg production (P > 0.05). Rearing diet had little long-term effect on any adult characteristics. There were significant (P < 0.01) strain effects on body weight, feed intake, and egg weight, although these were independent of rearing diet. In Experiment 2, regardless of bird strain, the pullets with smaller body weight matured more slowly (P < 0.01) and produced less total egg mass to 70 wk age (P < 0.05). These smaller birds ate less feed and produced smaller eggs (P < 0.01). There were strain effects, independent of 18-wk body weight, for egg weight and eggshell quality (P < 0.01). It is concluded that minor strain differences exist with respect to response to juvenile nutrition, although such effects are only evident in early lay. All strains of bird remain small, 18-wk body weight is reduced, and these birds subsequently eat less feed and produce smaller eggs.

Two experiments were carried out with male broiler chickens in which diets from 35 to 49 d of age were diluted by oat hulls and sand. In one experiment only energy was diluted; in the second experiment, both energy and protein (amino acid) levels were affected. Each diet was tested with four replicate floor pens each containing 25 1-d-old birds. All birds received a standard starter diet to 16 d and then grower diet to 35 d. In Experiment 1, dilution of only energy resulted in a significant linear (P < 0.01) reduction in body weight at 42 d, although there was growth compensation after this time such that all birds weighed the same at 49 d. Diet energy dilution resulted in increased feed intake, although energy intake was not maintained (P < 0.01). Diet energy dilution generally had little effect on carcass weight or yield of breast meat, although there was less abdominal fat (P < 0.01). In Experiment 2, dilution of both energy and protein had a comparable effect on growth rate as described in Experiment 1; however, in this study there was a linear decrease in carcass weight and breast meat yield as the diet was diluted. These results suggest that the male broiler chicken can grow quite well on very low energy diets but that a period of at least 7 d is required for adjustment to feed intake. Even with compensatory increase in feed intake, however, the bird is unable to maintain its energy intake when fed such diluted diets.

Male broiler chickens were fed corn-soybean diets providing 2,700, 2,900, 3,100 or 3,300 kcal ME/kg. In all experiments, each treatment was tested with three replicate groups of 30 birds grown to 49 d of age. In Experiment 1, birds consumed the various diets ad libitum whereas in Experiment 2, all birds received identical and restricted quantities of feed so as to ensure variable intakes of energy. In a third experiment, after 7 d of age, broilers had access to feed in two feeders that contained only the highest level of energy, or the 3,300 kcal ME/kg diet in combination with one of the other diets previously described. Providing diets of 2,700 to 3,300 kcal ME/kg for ad libitum consumption had no effect on growth rate (P > 0.05) and energy intake was constant; however, reducing the energy level of the diet did result in reduced carcass fatness (P < 0.01). When feed intake was controlled in Experiment 2, there was reduced growth (P < 0.01) rate as energy level of the diet was reduced. This reduced growth was associated with dramatic reduction in carcass fatness (P < 0.01), although breast meat yield was not affected. When broilers were offered a choice of diets, they showed remarkably precise control of intake, such that energy intake was again constant across all treatments. However, even though energy intake was constant, broilers consuming the choice diets involving the lower energy content diets tended to have less carcass fat. It is concluded that the broiler still possesses a good ability to control its feed intake based on desire to normalize energy intake. As energy intake is decreased, or there is increased protein intake, the bird deposits less carcass fat.

Two experiments were undertaken to study the response of White Leghorn hens to low dietary phosphorus levels from 18 to 64 wk of age. A corn-soybean meal diet containing .2% available phosphorus gave similar performance, up to 32 wk of age, as a similar control diet containing .4% available phosphorus. Beyond 32 wk, although shell quality and average egg weight were similar, egg production was significantly reduced with the lower phosphorus diet. Phosphorus excretion (grams per bird per day) averaged .47 g for .4% vs .28 g for .2% available phosphorus when measured at 28 wk of age. In a second experiment identical procedures and bird number as used in Experiment 1 were employed with the exception that the test diet contained .3% rather than .2% available phosphorus. No differences were noted for any of the production variables measured between the .4 and .3% available phosphorus diets. Phosphorus excretion data collected at 25, 32, 44, and 60 wk of age showed a decrease of approximately 20% for hens receiving the lower phosphorus diet. Indeed the overall average for phosphorus excretion for the lower phosphorus diet was calculated to be identical to the 20% lower total phosphorus content of this diet (.59 vs .47%).

White Leghorn chicks were fed corn-soybean meal diets containing 20, 17, 14, and 11% protein, with similar levels of energy, from hatch to 16 wk of age. Body weights at 16 wk were similar for pullets fed the 20 and 17% protein diets, but were reduced by 11 and 27% for birds fed the 14 and 11% protein diets, respectively, as compared with the 20% protein diet. At 16 wk of age, all birds were placed on a common 17% protein laying diet. Pullets fed the 14 and 11% protein laying diets were slightly slower coming into production, however, by 28 wk of age egg production was similar for all four growing treatment groups and remained so until the end of the experiment. Average egg weight was similar for pullets fed the two higher levels of protein during the growing period and significantly lower for those pullets fed the 11% grower diet for all except the 28- and 32-wk periods. Pullets fed the 14% grower diet produced eggs with average weights significantly lower than those for the higher protein diets from 40 to 58 wk of age. Although the results might be interpreted as indicating that higher protein growing diets result in body protein reserves that subsequently enhance egg size, it is more likely that the pullets consuming lower protein diets produce smaller eggs because they have smaller body weights.

Two experiments were undertaken to study the influence of prelay diet treatment on subsequent laying performance. Feeding either a conventional laying or growing diet or diets containing essentially only wheat bran from 18 to 21 wk resulted in little grower diet carryover effect beyond 24 wk of age, although the wheat bran diets resulted in a marked drop in body weight of the pullets during the prelay treatment. Similar performance was noted for pullets in a second experiment in which prelay treatments consisted of feeding just corn or wheat bran from 18 to 20 wk of age. In interpreting the results of the present study, it is important to consider the fact that "mature pullet weights" were obtained before the prelay diet treatments were employed. Where prelay diet treatments have had significant effects on laying house performance, in most cases, immature or underweight pullets were involved. Feeding hens low-protein diets (13 versus 17%) from 20 to 44 wk of age resulted in similar egg production; however, egg weight and thus egg mass were slightly reduced with the lower protein diet. There was no laying by growing treatment interaction. The importance of good pullet weight at the start of the production cycle and the subsequent performance of such pullets fed low-protein diets is discussed.

Several experiments were undertaken to investigate nitrogen excretion for laying hens fed diets varying in level of dietary protein. Reducing dietary protein levels from 19 to as low as 5% resulted in a concomitant decrease for up to 50% in nitrogen excretion. Depending on age of the hens, dietary protein levels as low as 11% gave reductions in nitrogen excretion for up to 40% when compared with a conventional 17% protein corn and soybean meal diet, with a minimum reduction in egg mass output. Because exceptionally high intakes of dietary protein are required to maximize egg size, there is merit to optimizing rather than maximizing egg mass output.

There is some evidence to suggest that the aetiology of 'Sudden Death Syndrome' (SDS) and ascites in broilers are closely related and that they may be the result of different degrees of the same metabolic condition. Many of the clinical findings, such as cardiac involvement and oedema are common to both conditions. Males are more affected than females and rapid growth, if a factor, is more related to increased oxygen demand rather than growth per se. Dietary, environmental or other factors which disrupt the balance of electrolytes, metabolites or pH may affect cardiopulmonary function and lead to SDS or ascites. The conditions can be either acute or chronic in nature and, whereas if acute, the end result is SDS, when chronic, ascites is the end result. Dietary or environmental factors that may either help to stabilize or adversely affect acid base balance may be useful avenues for future research into the aetiology of SDS and ascites. Factors that would increase the bird's capacity for supplying adequate oxygen to the tissues may also help to alleviate these two conditions which are of considerable annual cost to the poultry industry.

Two experiments were conducted to study the response of 35- to 49-day-old male broilers to either feed restriction or diet dilution. In Experiment 1, after being fed conventional starter-grower diets to 35 days of age, birds consumed either a conventional finisher diet ad libitum, or 10, 20, 30, 40, or 50% less of this diet to 49 days of age. Performance and carcass characteristics were measured from 35 to 42 days and 42 to 49 days. There was a linear relationship between nutrient intake and 42- and 49-day body weight (P < .01). However, as a percentage of the control birds, weight gain was reduced less from 42 to 49 days (64%) than from 35 to 42 days (86%) for the 50% restricted group. Thus, there was apparently an adaptation in the period from 42 to 49 days. In a second comparable experiment, birds were offered a conventional finisher diet or one with either 10, 20, 30, 40, or 50% dilution with a 50:50 (wt:wt) mixture of sand:oat hulls. Growth rate was only slightly reduced, thus demonstrating the remarkable ability of the broilers at this age to increase feed intake in response to energy density of the diet. Although birds were of comparable weight, diet dilution resulted in a linear reduction in size of abdominal fat pad, whereas breast weight was not affected. The present data suggest that broiler chickens are far from eating to physical capacity, at 35 days of age, because they were able to exhibit up to a 70% increase in feed intake relative to the control birds.

Three experiments were conducted with broiler chicks where diet composition varied with respect to dietary protein, energy, and essential amino acid (EAA) balance. Birds fed diets varying widely in EAA balance and protein and energy levels performed differently with respect to percentage carcass fat and protein. The absolute carcass protein deposition remained relatively constant between treatments, but body fat content varied depending on level of energy intake. Although abdominal fat content varied with level of dietary protein and energy, these values did not correlate well with total carcass fat deposition. Carcass fat deposition correlated well with dietary energy intake, which in turn appeared to be influenced by birds eating to satisfy their EAA requirement. With diets of similar EAA balance, birds appeared to have similar EAA intakes rather than similar energy intakes. Birds fed diets with similar EAA levels, but varying widely in level of nonessential amino acids, energy, or both consumed similar amounts of feed and deposited similar amounts of carcass protein. The present data suggest that level and balance of EAA can have a significant effect on feed intake, thereby influencing weight gain and carcass composition.

Chronic pain is a problem among patients with spinal cord injuries, but the psychosocial factors associated with spinal cord injury (SCI) pain are not well understood. To understand SCI pain further, 54 patients (19 with quadriplegia and 35 with paraplegia) completed the Beck Depression Inventory, State-Trait Anxiety Inventory, Profile of Mood States, Acceptance of Disability Scale and SCI Interference Scale. Forty-two patients stated they had SCI pain and completed the Multidimensional Pain Inventory and the Pain Experience Scale. Results revealed that anger and negative cognitions were associated with greater pain severity. Patients who reported pain in response to a general prompt experienced more severe pain than patients who reported pain only when directly questioned about the presence of pain, but these different reporting groups did not differ on emotional variables. Those who were less accepting of their disability reported greater pain severity. Additionally, patients who perceived a significant other expressing punishing responses (e.g., expressing anger at the patients or ignoring the patients) to their pain behaviors reported more severe pain. Level of lesion, completeness of injury, surgical fusion and/or instrumentation and veteran status were not associated with pain severity. Finally, pain was associated with emotional distress over and above the distress associated with the SCI itself. Overall, psychosocial factors, not physiological factors, were most closely associated with the experience of pain. Multidimensional aspects of pain are used to explain these findings and suggest that treatment should be directed at the emotional and cognitive sequelae of chronic SCI pain.

A series of experiments were conducted to evaluate the performance of 7- to 21-day-old broilers fed diets in which excesses of essential amino acids (EAA) were minimized. A 23% protein diet in which all EAA except TSAA were in excess was reduced in protein in a stepwise manner, keeping the corn; soybean meal ratio constant, to the point where all EAA were at minimum requirement level based on the 1984 National Research Council (NRC) requirements. Crystalline EAA supplemented those EAA that became deficient as dietary protein was reduced. Other test diets included one containing an additional 10% of the particular EAA in question and one with nonessential amino acids (NEAA) added to make the low-protein diet isonitrogenous with the 23% control. Performance of birds fed the low-protein test diets was not significantly different from that of the control birds. All EAA appeared to be adequate at levels recommended by the NRC in 1984 except Trp, which required .25% for optimal performance. A growth response was observed when Gly was used as the NEAA source; however, no response was noted when mixtures of NEAA were used as the NEAA source, suggesting that Gly may have been limiting in these earlier treatments. Total carcass protein of birds fed the low-protein test diets in which all EAA were minimized was equal to that of the control birds. In a final experiment utilizing the EAA-balanced, low-protein diet, dietary energy was allowed to vary by 15%. The EAA intake was constant, indicating that birds were eating to satisfy EAA requirements rather than energy requirements. Increased carcass fat deposition paralleled dietary energy increases.

Two experiments were conducted to investigate the effect of supplemental niacin on laying hen performance and liver fat and egg cholesterol content. In Experiment 1, 16 replicate groups of four adjacently caged birds were fed corn and soybean meal diets calculated to contain 22, 44, 66, or 132 mg supplemental niacin/kg (23.2, 38.7, 57.0, and 143 mg/kg niacin by analysis). Egg production, egg weight, feed intake, and eggshell quality were assessed each 28 days through a 364-day trial period. After 280 days, cholesterol content on three eggs per replicate was measured. At the end of the study, one bird per replicate was killed for subjective scoring of liver fat content. In Experiment 2, 24 birds from the control treatment (22 mg/kg supplemental niacin) of Experiment 1 were retained and fed for a subsequent 28-day period. Over this time, eight birds were each fed diets containing 22, 522, or 1,022 mg/kg supplemental niacin. Egg cholesterol content was measured in eggs collected on the last 3 days of the study. In Experiment 1, birds fed 66 or 132 mg/kg supplemental niacin/kg produced more eggs (P less than .05) than birds fed 22mg/kg. Niacin supplementation affected shell quality (P less than .05). Dietary niacin level had no effect on egg cholesterol content of liver lipid evaluation. In Experiment 2, supplementary niacin levels up to 1,022 mg/kg, which more closely stimulates therapeutic levels used for humans, again failed to affect egg cholesterol content.

Two experiments were conducted to note the response of broiler chickens to degrees of diet dilution from 4 to 11 days of age. In Experiment 1, broilers were fed conventional broiler diets from 0 to 4 and 11 to 56 days of age. From 4 to 11 days, birds were fed a conventional corn and soybean meal broiler starter, or the same diet in which major nutrients were replaced with 25, 40, or 55% ground rice hulls. Mineral and vitamin sources were not affected by dilution. Each of the three diluted diets together with an undiluted control diet was fed to three replicate floor pen groups of 30 male or 30 female broilers. In a second similar experiment, male birds were fed a regular broiler starter from 4 to 11 days or a diet diluted with 50% rice hulls. In this second experiment, rice hulls were substituted for all ingredients including those providing vitamin and mineral supplements. In Experiment 1, diet dilution resulted in a significant (P less than .05) reduction in body weight at 11 days of age, although by 42 days there was complete recovery of body weight with no change in overall efficiency of feed utilization. This same trend was seen in both sexes. Calculation of energy balance suggests these birds to have used energy very efficiently during the period of undernutrition. Diet dilution had no effect on carcass characteristics at 42 days, although for males at 56 days there was an indication of reduced abdominal fat content (P less than .05). In Experiment 2, compensatory gain was incomplete, although results were confounded due to an outbreak of infectious bronchitis.(ABSTRACT TRUNCATED AT 250 WORDS)

The present study was undertaken to investigate whether broiler chicks fed canola meal, as compared with diets of soybean meal, would respond to a higher level of supplemental calcium. Supplementing canola basal diets and soybean-meal basal diets with additional sulfur from sodium sulfate resulted in little or no change in broiler performance. However, supplementing diets with organic sulfur (cystine) caused a marked decrease in weight gain and feed intake, more severe with a canola diet than with a soybean-meal diet and which could be partially alleviated by increasing the calcium supplementation. A significant cystine-by-calcium interaction showed that feed intake dropped markedly, especially at the higher levels of calcium, as the levels of cystine supplementation increased. Part of the reduced performance, sometimes noted when diets supplemented with canola meal are used, may be due to a reduction in feed intake resulting from an interaction between dietary calcium and sulfur.

Male, Large White turkeys were reared to 28 wk of age on diets that varied in protein level after 16 wk of age. The diet composition had little effect on weight gain and feed utilization for birds evaluated at 20, 24, and 28 wk of age. The yield and composition of carcass parts were also affected very little by the dietary treatment. Body weight gain over time was fairly consistent to 28 wk of age. Feed utilization declined, especially between 24 and 28 wk of age. Age had a significant effect on the meat yield of the carcass parts. The percentage yield of breast meat was markedly increased from 20 to 28 wk of age, while the percentage yield of thigh and drumstick meat was reduced. While the absolute yield of edible protein increased with age, there was a noticeable increase in fat deposition, especially in the breast and thigh meat with birds that were 28 wk old versus 24 wk old.

Leghorn pullets of a commercial strain were cage-reared at densities of 293 or 586 cm2/bird. Diet treatments consisted of a control step-down protein program, a reverse-protein program, and two treatments involving 18% crude protein throughout rearing with modification of texture and energy concentration according to bird age. Thus, one treatment involved a crumbled low-energy diet to 10 weeks, followed by a crumbled high-energy diet to 16 weeks, while the alternate series involved a mash low-energy diet to 10 weeks followed by the crumbled high-energy diet to 16 weeks. Birds were weighed periodically throughout rearing and, when they were subsequently moved to laying cages, light was immediately increased from 8 to 14 hr. Irrespective of diet treatment, the more liberal density of 586 cm2/bird resulted in a 5 to 8% increase in feed intake (P less than .01). However, this increased intake was not associated with increased body weight (P greater than .05), and as confirmed by carcass analysis, it is assumed that this increased nutrient intake relates to increased maintenance requirement associated with bird activity. Birds offered the crumbled vs. mash high-energy diet to 10 weeks of age, consumed more feed (P less than .01), although change of diet texture from mash to crumble at 10 weeks failed to stimulate appetite. Also, birds reared on either the step-up energy programs were similar in weight to control-reared birds at 16 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study was conducted to determine the effect of two varieties of rapeseed meal at 10 and 20% levels in the diet on the productive performance, organ weights and liver lesions of two commercial strains of laying hens. The double-low (Brassica napus 1788) rapeseed meal appeared to be superior to Span meal (Brassica campestris) at the 10% level in maintaining egg production, feed efficiency, thyroid weight and body weight gain. However at the 20% level the productive performance was decreased in all the hens except the thyroid weights in the double-low group. Mortality caused by haemorrhagic liver syndrome was significantly higher among birds fed rapeseed meals than in the controls and was higher in the Span-fed groups than in those receiving the double-low variety. The two strains of birds showed no difference in mortality due to haemorrhagic liver syndrome. It was suggested that the lower level of glucosinolates in the double-low variety was responsible for the superiority of this meal over the Span meal.

Broiler breeder pullets of a commercial strain were allowed a free-choice of diets providing concentrated sources of protein (46.3% CP, 2487 kcal ME/kg) or energy (8.6% CP, 3218 kcal ME/kg). Three replicate floor pen groups of 22 birds each were compared with control birds consuming a regular diet ad lib. Diet self-selection had no effect on growth rate (P greater than .05), while calculation of nutrient intake indicated a dietary equivalent consumed of some 18% CP 0 to 4 weeks, some 13% CP 4 to 16 weeks, and 17% CP from 16 to 20 weeks. This pattern is discussed relative to previous findings with Leghorn pullets. In a second trial birds were fed a reverse protein program, with the following diets being provided ad lib: 0 to 12 weeks, 12% CP, 3080 kcal ME/kg; 12 to 16 weeks, 16% CP, 2974 kcal ME/kg; and 16 to 20 weeks, 19% CP, 2972 kcal ME/kg. Control birds received a regular feeding program, involving a restricted feeding schedule as recommended by the breeding organization. Each diet was tested with six replicate cages of 10 birds each. Up to 8 weeks-of-age reverse protein fed birds were smaller in body size than conventionally restricted birds. However, after this time, the converse was true.

Chicks with genetically elevated renal arginase activity were fed crystalline amino acid diets varying in ornithine concentration (0, 1 or 2%) to assess the potential for precursor regulation of polyamine synthesis. Renal arginase and renal and hepatic ornithine decarboxylase activities fell when ornithine was fed. Renal and hepatic ornithine concentrations rose while putrescine concentrations varied quadratically with ornithine feeding. Spermidine and spermine concentrations were not affected by diet. It was concluded that ornithine synthesized in vivo was a more potent stimulator of polyamine synthesis than ornithine of dietary origin.

White Leghorn pullets were fed corn-soybean meal diets containing .25 (control), .175, or .1% supplemental salt to 20 weeks of age, followed by a regular laying diet to 36 weeks of age. Body weight and feed intake of the growing pullet was significantly reduced with .1% salt compared to other treatments, while in early production these same birds produced fewer eggs compared with birds fed .25% salt during rearing. It is concluded that manipulation of dietary salt levels may be used to delay sexual maturity.

Two trials were undertaken to study the effect of nutrient intake on skeletal size in growing pullets. Leghorn chicks at 28 days were smaller in weight and shank and keel length when fed 16% as compared to 22% crude protein. Increasing the energy or mineral-vitamin concentration of the diet had no effect on skeletal parameters. Increased skeletal size of pullets in response to increased diet protein was associated with reduced (P less than .01) tibial ash content. In a subsequent trial, broiler breeder pullets were fed, ad libitum, starter diets (0 to 21 days) containing graded levels of protein from 20 to 13%. Reducing protein level had a consistent negative effect on body weight, shank length, and keel length at 21 days. When birds were subsequently fed restricted quantities of a common grower diet, no differences in body weight and skeletal parameters were evident at maturity. It is concluded that although early body weight and skeletal size can be markedly influenced by diet protein level, such effects are subsequently nullified by conventional restricted feeding programs.

Several experiments were undertaken to evaluate diets that could be used to bioassay methionine activity in various compounds. The following semipurified diets were tested: a corn-soy-gelatin basal (CSG) diet supplemented with essential amino acids (EAA) at 23% crude protein (CP); a soybean meal diet at 23% CP; and a soybean meal diet at 15% CP with all the protein coming from dehulled soybean meal and starch, glucose, and fat used as sources of energy. The CSG and 15% CP soybean meal diets proved to be sensitive in their response to methionine supplementation. Birds fed the CSG diet supplemented with methionine and tryptophan were smaller (P less than .01) than birds fed the 23% CP soybean meal diet, thus suggesting that something other than EAA was limiting the performance of birds fed this diet. Based on sensitivity to methionine supplementation, simplicity and cost of diet, the low protein soybean meal diet seems most appropriate for methionine bioassays.

The incorporation of L-methionine-3H(G) and L-lysine-4,5'3H(n) into egg albumen by dwarf and non-dwarf White Leghorn hens was studied together with the influence of exogenous triiodothyronine (T3) and tetraiodothyronine (T4) on those incorporation patterns. The results were influenced by the amino acid studied and by the strain of bird. The maximum uptake of methionine was a day 1 for the normal and at day 4 for the dwarf which suggested that the dwarf was storing methionine in the tissue first before incorporation into albumen. If the birds were given T3 the maximum for the normal was at day 1 and day 3 for the dwarfs. When T4 was given the maximum uptake was found at day 5 for normals, and at day 2 for dwarfs. In the dwarf, T4 administration essentially corrected the decreased rate uptake of methionine but markedly retarded its uptake by the normal birds. The results for lysine were quite different. The maximum uptake was on day 4 in control, day 3 for T3-treated and day 1 for T4-treated, normal birds. In dwarf birds, the maximum was at day 2 for the control and T4-treated, and day 4 for T3-treated groups. The data were interpreted to suggest strain differences in amino acid uptake patterns due to different rates of synthesis or composition of egg albumen and marked differences in response or recptor sites to thyroid hormones.

An experiment was undertaken to test the response of dwarf broiler pullets when fed on two planes of nutrition in the growing period and fed either a 17 or 19% protein diet in the breeder house. Pullets offered 20% more feed in the growing period were heavier at 21 weeks of age and reached 50% egg production 2 weeks earlier than birds fed the regular diet. Pullets fed 20% more feed in the growing period and full-fed to 26 weeks in the laying house, gained appreciably more weight, and although they came into production faster, were less persistent in lay than birds fed the regular diet. There was no difference in egg production, egg size, or body composition of dwarfs fed 17 or 19% breeder diets.

Diets containing either 22 or 30% protein were supplemented with a vitamin mix where one of 11 added vitamins were singly eliminated from the mix. Male, day-old broilers were fed these diets to 3 weeks of age, and weight gains, feed utilization, and leg problems were recorded. In general, the higher protein diet did not result in a greater incidence of leg problems; however, it did alter performance of several of the vitamin-deficient diets as compared to the lower protein diet. Of the 11 vitamins studied only nonsupplementation of riboflavin markedly reduced weight gain and feed utilization during the 3-week feeding period. However, deletions of vitamin D3 and niacin also resulted in reduced performance. Riboflavin deficiency resulted in paralysis in a high percentage of the birds while the niacin-deficient diet gave a high percentage of birds with deformed legs and problems of mobility. The results demonstrate that a high incidence of leg problems may be present in a flock with little or no signs of reduced gain or feed utilization. The data suggest that under practical conditions the elimination of a particular vitamin from a diet for a short period of time would probably have a negligible effect on performance.

Jejunal tissue was taken from 18-week-old broiler breeder pullets previously reared on a daily or skip-a-day feed restriction system. Light and scanning electron microscopy revealed no changes in mucosal appearance or structure related to feeding system. Comparable duodenal samples all revealed extensive desquamated epithelial damage possibly related to postmortem change.

An experiment was conducted to determine the effect of feeding ornithine in combination with alpha-aminoisobutyric acid (AIB), an inhibitor of arginase, on the regulation of polyamine synthesis in chicks. A total of 48 chicks with genetically elevated renal arginase activity was fed diets containing crystalline amino acids and 1% AIB with or without 2% ornithine. Feeding AIB reduced renal arginase activity, while renal and hepatic ornithine decarboxylase (ODC) activity increased. Feeding AIB plus ornithine caused no further reduction in renal arginase activity compared with that in chicks fed the AIB-supplemented diet. Renal and hepatic ODC activities, however, fell to below control levels. Renal, hepatic, and breast muscle ornithine concentrations increased substantially when ornithine was fed. AIB plus ornithine increased renal putrescine and spermidine concentrations. It was concluded that AIB could partially overcome the ornithine-induced inhibition of ODC activity. These findings support the hypothesis that dietary manipulation of precursor amino acids of polyamines in the presence of metabolites that induce ODC activity can influence tissue polyamine concentrations.

Experiments were conducted to determine the effect of dietary lysine on hepatic and renal polyamine synthesis in the chick. High arginine-requiring (HA) and low arginine-requiring (LA) strains were used, with differences in arginine requirements being due, in part, to differences in renal arginase activity. Arginine requirements were 1.2 and 0.9% for the HA strain and LA strain, respectively. A total of 96 chicks (16 per diet, 48 per strain) were fed a crystalline amino acid diet containing requirement concentrations of arginine and 0.95, 1.40 or 1.85% lysine for 2 wk. Hepatic arginase activity was unaffected by dietary lysine in both strains, whereas hepatic ornithine decarboxylase (ODC) activity fell with increased dietary lysine in the LA strain only. Increasing dietary lysine significantly increased renal arginase activity but reduced renal ODC activity in the HA strain only. Increasing dietary lysine also caused decreased renal concentrations of arginine, whereas lysine and ornithine concentration increased in both strains. Concentrations of putrescine also rose. It was concluded that excess dietary lysine increased renal concentrations of ornithine due to induction of arginase. This accumulation of polyamine precursors resulted in increased concentrations of putrescine despite feedback inhibition of ODC.

Summers et al., 1978, described an experiment in which performance and leg conditions of birds fed diets devoid of synthetic biotin, choline, folic acid, manganese, and miacin were observed and recoreded. This is a report on birds from the same experiment. Dyschondroplasia of the tibia was documented and the distal end of each tibia examined histologically. Metatarsal length and condyle depth of the distal tibia were also determined. Metatarsal length was influenced by vitamin deficiencies as well as the type of floor on which binds were raised. The depth of the intercondyle space was affected more by a manganese deficiency than by vitamin deficiencies and, in this case, was greater on plastic and litter as opposed to wire floors. There did not appear to be a correlation between the space depth and slipping of the tendons; however, a large number of birds should be examined to provide more data. Dyschondroplasia was more prevalent in choline deficient birds, particularly those birds raised on litter or plastic floors. Histology changes in relation to nutrient deficiencies were comparable to those reported previously.

The influence of exogenous triiodothyronine (T3) or tetraiodothyronine (T4) on the incorporation of 3H-labelled methionine, alanine and lysine into plasma, liver and kidney was studied in 4 wk. old dwarf and non-dwarf female, White Leghorn chickens. The response to exogenous T3 or T4 of the birds was directly dependent on the dwarf status as well as the tissue and/or amino acid studied. In general, there was a decreased amino acid uptake by dwarfs and T3 and/or T4 depressed amino acid uptake in all combinations studied except for the uptake of lysine by the kidney of the dwarf. In that tissue, T4 administration caused a significant increase in lysine incorporation. The results found probably were due to different tissue amino compositions or rates of synthesis of proteins by dwarf birds when compared to normals and a differential sensitivity of dwarf birds to changed T3/T4 ratios.

Serum protein profiles were studied together with serum binding sites and capacity for L-thyroxine in dwarf and non-dwarf White Leghorn and White Rock breeds at ages 1 wk., 4 wks. and in laying hens. Serum protein profiles varied with breed, strain and age. The percent gamma-globulin fraction was greater (P less than .05) in dwarf 1 wk. old and laying hens of the White Leghorn breed when compared with the normals. The only difference found in the White Rock breed was a decreased level of albumin in dwarf laying hens. There were no significant differences in the capacity or sites of binding of L-thyroxine to serum proteins although greater amounts of L-thyroxine were bound to globulin fractions in the dwarf. The data were interpreted to suggest that changes in serum protein profiles may have been the result of hypothyroidism at the cellular level but there was no reason to suspect abnormal binding of thyroid hormones to be the cause of that hypothyroidism.

Two trials were conducted to note the effect of immature body size of leghorn pullets on subsequent laying performance, and in particular, egg size. In Trial 1, birds were classified as small, medium or heavy at 15 wk of age (997, 1,100, and 1,226 g, respectively). In Trial 2, segregation at 19 wk resulted in groups with mean weights of 1308, 1411, and 1564 g, respectively. In each trial, weight groups were represented by 40 replicate groups of four individually caged birds. Original weight groupings were maintained throughout the trials (P less than .05). In both trials, immature weight classification had a consistent effect on both feed intake and egg weight (P less than .05); larger birds consumed more feed while producing larger size eggs. In Trial 1, medium weight birds produced more eggs over the 52 wk. Similarly, smaller weight birds produced more eggs than did heavy birds (P less than .05). In Trial 2, weight grouping had no overall effect on egg production, although during the 19 to 23-wk period, heavy birds produced more eggs (P less than .05). It is concluded that immature body weight (15 to 19 wk age) can influence egg weight and that this relationship is linked to levels of nutrient intake. Each 100-g increase in body weight was associated with approximately 3.5 g increase in feed intake and 1.2 g increase in egg weight.

An experiment was conducted to examine the effect of previous diet on feed intake and weight gain, in the subsequent period, for broiler and Leghorn cockerels. Three dietary treatments, consisting of 20% protein and either 2400, 2800, or 3200 kcal Me/kg, were fed in combinations consisting of three, 2-week periods, with nine combinations in all. The experimental design was balanced for residual effects, and period weight gains and feed intake were determined. Analysis of the data by period indicated that treatments by residual interactions were confined to the final period. Therefore, it was concluded that diets fed in the previous two periods may be acting in combination to effect weight gain and feed intake in the final period. Examination of the pooled period data indicated that for optimum performance, broilers required a dietary regimen consisting of increased calorie-to-protein ratios with time while Leghorns required lower calorie-to-protein ratios. Type differences were also observed in the ability to adapt to high protein, low intakes: Leghorns grew optimally but body weight gain for broilers was reduced with such a feeding program.

A total of 192 Single Comb White Leghorn pullets were divided into three groups to study the effect of heat stress and diet composition on feed intake and laying performance at 21, 25, and 33 weeks of age. For each age group all birds were fed a control diet [17.1% crude protein (CP), 2770 kcal metabolizable energy (ME)/kg] for a 7-day period. During this time they were kept at a temperature of 18 C. The temperature was then immediately increased to 35 C, and groups of 16 birds offered either the control diet, a high protein diet (43.5% CP), a high energy diet (3371 kcal ME/kg), or a diet of high nutrient density (28.3% CP, 2842 kcal ME/kg, and 6.5% Ca) for a 3-day period. After the 3-day test period, temperature was returned to 18 C, although birds were still offered the experimental diets for an additional 4 days prior to returning to the control diet. Production parameters were measured for individual birds. Feed consumption, egg production (except for the 21-week-old birds), egg weight, and egg shell thickness decreased (P less than .05) with heat stress. Increases in energy and calcium intake helped partially to maintain normal egg production, egg weight, and egg shell deformation. Egg weight and egg shell deformation returned to pretest levels within an 8-week postexperimental period. With the exception of those birds receiving the control and high nutrient density diets at 21 weeks of age, data collected over the test periods showed that heat stress caused a significant reduction (P less than .05) in liveweight birds.

Experiments have been conducted to study the hypothyrotic status of chicks fed rapeseed meal. Protamone supplementation did not correct growth depression due to feeding rapeseed meal although inclusion levels up to 0.1% may have induced a hyperthyrotic condition which in itself leads to a growth depressing effect. Changes in liver and carcass composition were observed when diets containing rapeseed and soybean meal were supplemented with protamone and thiouracil. It is concluded that although birds fed rapeseed meal are abnormal with respect to thyroid metabolism, it is likely that factors other than a simple reduction in serum thyroxine concentration are responsible for the growth depression observed for such birds.

Leghorn pullets of a commercial strain were subjected to a conventional light program of constant photoperiod or an intermittent programming involving, during the house of conventional "lights-on", 45 min light (L): 15 min dark (D) from 24 to 27 weeks of age; 30 min L:30 min D from 28 to 35 weeks; and 14 min L:45 min D from 36 weeks to the duration of the trial. Each light treatment was tested with 12 replicate groups of 14 individually caged birds housed in adjacent rooms, with all birds fed a standard 15% crude protein, 2750 kcal ME/kg diet. Intermittent lighting resulted in a significant (P less than .05) reduction in feed intake and a consistent but nonsignificant (P less than .05) reduction in egg production. Egg size, egg shell quality, and albumen quality, as assessed by Haugh units, were not affected by light treatment. Due to the effect on egg production, it is concluded that intermittent lighting programs should not be initiated close to time of peak egg production.

A number of experiments were conducted to verify the sensitivity of a low protein (15%) soybean diet for assaying methionine (Met) activity. Although a good response in weight gain and feed:gain ratio was obtained with the addition of supplemental Met to the basal diet, an inconsistent response was obtained when the efficacies of DL-Met and liquid methionine hydroxy analogue (MHA were tested). The addition of nonessential amino acids produced a variable response when added to diets containing MHA, with no difference in the response to aspartic acid or a glycine/glutamic acid mix as nitrogen sources. The addition of glycine to diets supplemented with DL-Met resulted in improved performance with the highest level of Met supplementation, thus suggesting that glycine may be alleviating some deficiency in the high supplemental Met diet. Based on the results of several experiments, MHA was judged to be less efficient than DL-Met on a weight basis.

Day-old male broiler chickens were fed diets containing 0, 5, 10, 15, or 20% raw, ground, full-fat canola for a period of three weeks. Increasing the dietary proportion of full-fat canola significantly reduced feed intake (P less than .05) and weight gain (P less than .01), without altering feed:gain ratio. Diet had no significant effect on protein retention although there was a significant decrease in fat retention with an increase in dietary levels of full-fat canola (P less than .01). This was accompanied by a significant decrease in metabolizable energy (P less than .01). Increasing the proportion of dietary full-fat canola significantly reduced the concentration of soap in the digesta (P less than .05) and excreta (P less than .01). There was no significant effect of the dietary treatments on calcium or phosphorus retention. There was also no effect of the dietary full-fat canola on bone ash, bone calcium, or phosphorus content.

Large White male turkeys were reared in floor pens to 20 wk of age. Diet changes were made every 4 wk, with dietary energy levels kept similar for diets within a period, and changes made in protein levels. Although significant differences in weight were noted at 4 and 8 wk, these diminished with age such that at 20 wk no significant differences were noted. Feed intakes paralleled weight gains. A sample of birds was taken every 4 wk for a measurement of breast meat (excluding skin) and composition. Although changes in dietary protein levels did not affect weight gains to 20 wk of age, breast protein yields were significantly reduced by lowered dietary protein levels. Breast meat varied from 15% of live weight at 4 wk of age to 23% at 20 wk. Protein composition of breast meat varied between 90 and 95% (DM basis), and was estimated to be in excess of 50% of edible carcass protein. With such a high level of edible carcass protein coming from breast meat, it is suggested that yield of breast protein be used as a parameter in determining optimum protein and amino acid requirements of heavy weight turkeys.

Three experiments were conducted; the first studied the influence of pre-laying dietary calcium levels on subsequent hen performance, while in the second and third the influence of various levels of dietary calcium and phosphorus on performance, egg shell quality and calcium and phosphorus retention were investigated. Pre-dietary calcium levels (0.5 and 1.5%) resulted in a significant strain X diet interaction for weight gain up to commencement of lay but did not influence production, feed intake, egg size or sheel quality. Dietary calcium levels varying from 2.5 to 4.0% did not significantly alter the avove parameters during a 140 day laying test. Compared to a non-pelleted control diet, steam pelleting resulted in a significant enhancement in phosphorus availability is judged by higher levels of performance. Percent calcium retention varied with the level of dietary calcium and there was an indication that level of dietary phosphorus influenced calcium retention. Lower levels of dietary phosphorus resulted in egg shells with slightly lower deformation values. Regardless of dietary phosphorus, retention values were quite low. Changing the level of dietary calcium and phosphorus had little or no effect on the retention of phosphorus thus suggesting a relatively constant and low requirement for this nutrient.

The universal scatter function for natural water produces beam spread patterns in multiple forward scatter which remain compact in time and angular subtense, even neglecting absorption.

Male broilers were fed on isocaloric diets containing 140, 180 or 220 g/kg crude protein from 1 to 3 weeks of age. Four diets were formulated for each protein concentration so that essential amino acids (EAA), all balanced in proportion to requirement, supplied 350, 450, 550 or 650 g/kg crude protein. Weight gain, efficiency of food utilisation and total carcase protein reached plateaux at 550 g EAA/kg protein irrespective of the dietary protein content, whereas the proportion of carcase fat decreased and that of carcase protein increased as the proportion of EAA in the dietary protein increased. All EAA in the diet containing 550 g EAA/kg protein were supplied at 125% of requirement, suggesting that the amino acid requirements as reported are inaccurate. Weight gain and carcase protein were shown to be significantly (P less than 0.001) dependent on total intake of EAA rather than on the proportion of EAA in the diet per se. In order to supply sufficient EAA for maximum gains, the diet had to contain more than 140 g crude protein/kg and 450 g EAA/kg protein.